title: Identification and characterization of the channel-forming protein in the cell wall of Corynebacterium amycolatum.
abstract: The mycolic-acid layer of certain gram-positive bacteria, the mycolata, represents an additional permeability barrier for the permeation of small water-soluble solutes. Consequently, it was shown in recent years that the mycolic acid layer of individual bacteria of the group mycolata contains pores, called porins, for the passage of hydrophilic solutes. Corynebacterium amycolatum, a pathogenic Corynebacterium species, belongs to the Corynebacteriaceae family but it lacks corynomycolic acids in its cell wall. Despite the absence of corynomycolic acids the cell wall of C. amycolatum contains a cation-selective cell wall channel, which may be responsible for the limited permeability of the cell wall of C. amycolatum. Based on partial sequencing of the protein responsible for channel formation derived from C. amycolatum ATCC 49368 we were able to identify the gene coram0001_1986 within the known genome sequence of C. amycolatum SK46 that codes for the cell wall channel. The corresponding gene of C. amycolatum ATCC 49368 was cloned into the plasmid pXHis for its expression in Corynebacterium glutamicum ∆porA∆porH. Biophysical characterization of the purified protein (PorAcoram) suggested that coram0001_1986 is indeed the gene coding for the pore-forming protein PorAcoram in C. amycolatum ATCC 49368. The protein belongs to the DUF (Domains of Unknown Function) 3068 superfamily of proteins, mainly found in bacteria from the family Corynebacteriaceae. The nearest relative to PorAcoram within this family is an ORF which codes for PorAcres, which was also recognized in reconstitution experiments as a channel-forming protein in Corynebacterium resistens.
authors.affiliation: School of Engineering and Science, Jacobs University Bremen, Campusring 1, 28759 Bremen, Germany.
authors.forename: Nafiseh
authors.initials: N
authors.lastname: Soltan Mohammadi
authors.forename: Samaneh
authors.initials: S
authors.lastname: Mafakheri
authors.forename: Narges
authors.initials: N
authors.lastname: Abdali
authors.forename: Iván
authors.initials: I
authors.lastname: Bárcena-Uribarri
authors.forename: Andreas
authors.initials: A
authors.lastname: Tauch
authors.forename: Roland
authors.initials: R
authors.lastname: Benz
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002473:Cell Wall / Q000378:metabolism*; D003001:Cloning, Molecular; D003352:Corynebacterium / Q000378:metabolism*; D017931:DNA Primers; D004352:Drug Resistance, Microbial; D008051:Lipid Bilayers; D008969:Molecular Sequence Data; D018272:Porins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D008051:Lipid Bilayers; D018272:Porins; D011994:Recombinant Proteins
keywords: Cell wall channel; Corynebacterium amycolatum; DUF3068 protein family; Lipid bilayer membrane; Mycolic acid; Porin